GB1562402A

GB1562402A - Tower packing element

Info

Publication number: GB1562402A
Application number: GB3431276A
Authority: GB
Original assignee: LEVA M
Current assignee: LEVA M
Priority date: 1976-08-18
Filing date: 1976-08-18
Publication date: 1980-03-12

Description

(54) TOWER PACKING ELEMENT (71) I, MAX LEVA, a citizen of the United States of America, and residing at 1 Hodgson Avenue, Pittsburgh, Pa15205, United States of America, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a novel tower packing element for use in random poured packed beds in towers and columns, to bring about mass and heat transfer in gas absorptions, distillations, reactors and similar apparatus extensively used in chemical and physical operations.

The most commonly used packings for such purposes are various sizes of rings and saddles. Although widely used, these packings all suffer from the same shortcom ings,-namely, they will not really form truly physically stable packed beds. Thus, in the randomly poured beds composed of rings and saddles, the pieces are not truly individually interlocked and will, therefore, with time, continue to shift and settle in the towers. This shortcoming has the obvious disadvantage that the flow resistance, which these beds will offer to the fluids that are passing through them, will steadily increase.

Pressure drops and energy requirements for pumping are, therefore, very difficult to predict in advance, for such packings, with any great degree of assurance, because these quantities are forever changing.

Another severe shortcoming of the various ring and saddle packings is due to the fact that the beds, formed by these packings, are not truly homogeneous in theor texture.

With rings, one always finds large numbers of the pieces aligned in tandem arrangement. This tandem arrangement is particularly objectionable because a channel is thus formed that is ideal for passing the liquids downwardly, and the liquids are thereby often entirely separated from the gas phase that moves along somewhere else.

This separation of flows, which is virtually impossible to control and prevent, is one of the reasons why the contacting efficiencies of these packings are not accurately predictable. Furthermore, this separation of the phases results, in all instances, in a low contacting efficiency. With saddles, the pieces tend to "nest", which is a generally accepted term with saddles, to indicate that the pieces will build up into stacks,-the individual pieces fitting into each other snugly and preventing large portions of the packing surfaces from becoming accessible to the flowing liquid and gas phases. Obviously, nesting is, therefore, a major cause of poor contacting efficiency. Thus it is seen that the usual ring and saddle packings offer, in their randomly dumped beds, substantial regions of high and low local packing densities. As already stated, this undesirable situation leads to channeling of the liquids and hence to actual physical separations of the gas and liquid phases. The result is that these packings are much less effective to bring about heat and mass transfer between the liquid and gas or vapour phases than could be achieved if the packings would not encourage this phase separation.

This invention results from attempts to provide a novel tower packing element which can help to overcome the aforementioned shortcomings of existing elements.

According to the invention I provide a tower packing element formed from a substantially rectangular strip of sheet material that is cut and bent to define an arcuate base with a slot in it, and to define a tongue, the base extending through an angle, as hereinafter defined, of substantially 90" to substantially 1800, and the tongue consisting of material that occupied the slot in the uncut strip, and being displaced from the surface containing the base.

The angle through which the arcuate base extends is hereby defined as the angle between the normals to the tangents at the ends of the arc.

The packing element may be constructed of any metal or plastics sheeting, clay or ceramic product or other that permits the formation of the element by various means.

Preferably the tongue is cut and displaced from the strip by a striking operation, and the strip is then rolled to produce the curved base.

Generally speaking, it will be satisfactory for the base to have the shape of any open ended curved surface, as, for instance, the shape of a quarter to a semi-circle, a quarter to a semi-ellipse, parabola, hyperbola or that of any other similar open ended curve.

The slot preferably extends substantially parallel to the circumferential direction of the base, but it could be arranged to extend transversely to that direction if desired.

Preferably the base extends through an angle of substantially 90 or substantially 1800.

The tongue may be situated radially outwardly from the base, but preferably it is situated radially inwardly from the base.

When the tongue is situated radially inwardly of the base an advantageous arrangement is one in which the free end of the tongue is located substantially on the chord extending between the ends of the base. This assists greatly in preventing nesting.

The packing element may be provided with more than one tongue, and the tongues may be associated with respective slots, each tongue being supported from the base to an end of a respective slot.

The invention enables the provision of packing elements whereby more pieces may be packed into a unit volume than with comparable sizes of the various ring and saddle packings whereby there is more surface area in a unit volume; and whereby virtually all the surface area of the packing is accessible to liquid and gas phases, providing the packing with greatly superior mass transfer and heat transfer characteristics than comparable sizes of the various presently used ring and saddle packings.

Various packing elements suitable for use in random poured packed beds and in accordance with the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a front, elevational view of a packing element provided with a single tongue; Figure 1a shows a modification of the element of Fig. 1 in which the base extends through an angle of 90 ; Fig. 2 is a side view of the element of Fig. 1 as viewed from the right in Fig. 1; Fig. 3 is a front view of an element employing a plurality of tongues; Fig. 4 is a side view of the element of Fig. 3 as viewed from the right in Fig. 3; Fig. 5 is a view similar to that of Fig. 4 but showing a modification; Fig. 6 is a front view of an element provided with two tongues which are situated radially outwardly from the base; Fig. 7 is a front view of a further element in which the tongues are situated alternately radially outwardly and inwardly from the base.

Fig. 8 shows a front view of a further element; Fig. 9 shows a front view of yet a further element including two rows of tongues in which all of the tongues are situated radially inwardly from the base but extend in opposite directions in the two rows; and Fig. 10 is a side view of the construction shown in Fig. 9 as viewed from the right thereof.

The packing element of Figures 1 and 2 has been formed from a rectangular strip of sheet material by cutting and bending.

The element comprises a base 1 having the shape of half of a circular-cylinder, an angle of 1800 being defined between the normals to the tangents to the arc at the ends 11 of the base. A curved tongue 3 is situated radially inwardly of the base 1 and is supported from the base at one end 21 of a slot 2 of rectangular outline and of which the other end is indicated at 211 in Figure 2. Tongue 3 is of the shape of part of a circular-cylinder of radius less than the radius of base 1. The element of Figures 1 and 2 has been produced from a rectangular strip by subjecting the strip to a striking operation to cut and displace the tongue from the plane of the strip, and then rolling the apertured strip into a semi-circular arc to produce the base. It will be seen from Figure 2 that the slot 2 extends parallel to the circumferential direction of the base 1, and from Figure 1 that the axis about which the tongue 3 is curved is parallel to the axis about which the base 1 is curved.

The modified element of Figure la has been formed in a similar manner to that of Figure 1 but in this case the base 1 has been rolled such that it extends through an angle of 90 , an angle of 90" being defined between the normals to the tangents to the ends of the arc.

The depth to which the tongue 3 reaches downwardly, with respect to the base 1 when the base is orientated as shown in Figures 1 and la, may be important to prevent nesting. In the instances of Fig. 1, the tongue 3 extends almost all the way to the axis of curvature of the base and substantially to the chord extending between the ends 11 of the base 1. It is apparent that this will be very effective to prevent nesting.

If Fig. la, the tongue 3 extends down less far in proportion to the radius of curvature R of the base, roughly about one fifth of a radius into the quadrant subtended by the base. For most purposes, the tow lengths of tongues described in terms of the radius R and ranging from R to R are most useful.

5 For best results, the tongues should, with semi-circular or near semi-circular bases, extend almost to the axis of curvature of the base.

It will be noted that the tongues shown in Figs 1 and la are curved circularly.

Obviously they could be shaped to follow curves other than a portion of a circle.

Fig. 3 shows a packing element provided with five tongues 5, 6, 7, 8, 9, which extend about two thirds of the radius R toward the axis of curvature of the base.

Fig. 4, shows the same packing in a side elevation and reveals that the various tongues which have been forced out of the strip to leave slots are arranged in two side by side parallel rows extending circumferentially of the base. By having offset the slots in these rows in the circumferential direction, a better distribution of tongues below the base has been achieved.

It has been observed that with a plurality of slots and tongues the mass transfer performance in a bed of the elements is greatly enhanced, because the internal liquid distribution in the packed bed is greatly improved, the greater the number of slots and tongues of the individual packing elements. Hence, with instances where mass transfer requirements beyond the ordinary are required, one would attempt to specify packing elements having as great a number of slots and tongues as possible.

The slots and tongues may be of different shapes. This is clearly shown in Fig. 5, where round ended slots 11, trapezoidal slots 12 and triangular slots 13 and tongues are shown, it being understood that the packing may instead have only slots of any one kind.

Clearly, other shapes of slots could be used if desired.

Fig. 6 shows an embodiment of the invention where the resulting tongues 14 have been displaced and bent radially outwards from the base 1 thus pointing away from the axis of curvature of the base. In all, two tongues are shown.

Fig. 7 shows an element in which the tongues 15, 16 of separate rows have alternately been bent radially outwardly and inwardly from the base 1, all the tongues of each row pointing in the same direction.

For this design, a minimum of two rows of slots will be required.

Fig. 8 similarly shows tongues 17, 18 extending radially inwardly and outwardly of the base respectively, however in this case the tongues alternately point in opposite directions in each row.

Figs. 9 and 10 show an element provided with two rows of slots and tongues, the tongues of one row extending in the opposite direction to those of the other row, and each slot being circumferentially aligned with a corresponding slot of the other row, with the result that corresponding tongues 19 and 20 of the two rows are seen to cross each other when the element is viewed as in Fig. 9.

In a modification, not illustrated, of the element shown in Figs. 9 and 10 the tongues 19 and 20 are struck from the same slot, instead of from separate slots, to eliminate the material 21, shown in Fig. 10, of the base 1 between the corresponding slots of the two rows. Thus in the modification two tongues are supported from the base at opposite ends respectively of each slot, and the material which occupied each slot in the uncut strip has been used to produce two tongues.

Thus it will be seen from the various embodiments of the invention described, that such packing elements can yield a stable and nonshifting packed bed and there will be substantially no nesting. Thus they will improve upon the operational stability that is obtained with conventional packing elements. Furthermore, it has been found that in randomly dumped beds of such packing elements there are a vastly greater number of point-to-point contacts between adjacent and near-adjacent packing elements.

This greater number of bodily contacts within the dumped beds will greatly assist in the co-ordinated direction of the irrigating liquid downward through the packed bed, thereby yielding better utilization of the physical contact area provided by the bed and thereby increasing the efficiency of functioning of the beds in an important measure.

WHAT I CLMM IS:- 1. A tower packing element formed from a substantially rectangular strip of sheet material that is cut and bent to define an arcuate base with a slot in it, and to define a tongue, the base extending through an angle, as hereinbefore defined, of substantially 90" to substantially 1800, and the tongue consisting of material that occupied the slot in the uncut strip, and being displaced from the surface containing the base.

2. A tower packing element as claimed in Claim 1 in which the base extends through an angle of substantially 1800.

3. A tower packing element as claimed in Claim 1 or Claim 2 comprising a further tongue, said further tongue also consisting of material that occupied said slot in the uncut strip.

4. A tower packing element as claimed in Claim 3 in which the tongues are supported from the base at opposite ends respectively of the slot.

5. A tower packing element as claimed in Claim 1 in which the base extends through an angle of substantially 90".

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. R and ranging from R to R are most useful. 5 For best results, the tongues should, with semi-circular or near semi-circular bases, extend almost to the axis of curvature of the base. It will be noted that the tongues shown in Figs 1 and la are curved circularly. Obviously they could be shaped to follow curves other than a portion of a circle. Fig. 3 shows a packing element provided with five tongues 5, 6, 7, 8, 9, which extend about two thirds of the radius R toward the axis of curvature of the base. Fig. 4, shows the same packing in a side elevation and reveals that the various tongues which have been forced out of the strip to leave slots are arranged in two side by side parallel rows extending circumferentially of the base. By having offset the slots in these rows in the circumferential direction, a better distribution of tongues below the base has been achieved. It has been observed that with a plurality of slots and tongues the mass transfer performance in a bed of the elements is greatly enhanced, because the internal liquid distribution in the packed bed is greatly improved, the greater the number of slots and tongues of the individual packing elements. Hence, with instances where mass transfer requirements beyond the ordinary are required, one would attempt to specify packing elements having as great a number of slots and tongues as possible. The slots and tongues may be of different shapes. This is clearly shown in Fig. 5, where round ended slots 11, trapezoidal slots 12 and triangular slots 13 and tongues are shown, it being understood that the packing may instead have only slots of any one kind. Clearly, other shapes of slots could be used if desired. Fig. 6 shows an embodiment of the invention where the resulting tongues 14 have been displaced and bent radially outwards from the base 1 thus pointing away from the axis of curvature of the base. In all, two tongues are shown. Fig. 7 shows an element in which the tongues 15, 16 of separate rows have alternately been bent radially outwardly and inwardly from the base 1, all the tongues of each row pointing in the same direction. For this design, a minimum of two rows of slots will be required. Fig. 8 similarly shows tongues 17, 18 extending radially inwardly and outwardly of the base respectively, however in this case the tongues alternately point in opposite directions in each row. Figs. 9 and 10 show an element provided with two rows of slots and tongues, the tongues of one row extending in the opposite direction to those of the other row, and each slot being circumferentially aligned with a corresponding slot of the other row, with the result that corresponding tongues 19 and 20 of the two rows are seen to cross each other when the element is viewed as in Fig. 9. In a modification, not illustrated, of the element shown in Figs. 9 and 10 the tongues 19 and 20 are struck from the same slot, instead of from separate slots, to eliminate the material 21, shown in Fig. 10, of the base 1 between the corresponding slots of the two rows. Thus in the modification two tongues are supported from the base at opposite ends respectively of each slot, and the material which occupied each slot in the uncut strip has been used to produce two tongues. Thus it will be seen from the various embodiments of the invention described, that such packing elements can yield a stable and nonshifting packed bed and there will be substantially no nesting. Thus they will improve upon the operational stability that is obtained with conventional packing elements. Furthermore, it has been found that in randomly dumped beds of such packing elements there are a vastly greater number of point-to-point contacts between adjacent and near-adjacent packing elements. This greater number of bodily contacts within the dumped beds will greatly assist in the co-ordinated direction of the irrigating liquid downward through the packed bed, thereby yielding better utilization of the physical contact area provided by the bed and thereby increasing the efficiency of functioning of the beds in an important measure. WHAT I CLMM IS:-

1. A tower packing element formed from a substantially rectangular strip of sheet material that is cut and bent to define an arcuate base with a slot in it, and to define a tongue, the base extending through an angle, as hereinbefore defined, of substantially 90" to substantially 1800, and the tongue consisting of material that occupied the slot in the uncut strip, and being displaced from the surface containing the base.

6. A tower packing element as claimed

in any of the preceding claims in which each tongue is situated radially inwardly from the base.

7. A tower packing element as claimed in any of the preceding claims in which the longitudinal axis of each tongue is curved, and the radius of curvature of each tongue is less than that of the base.

8. A tower packing element as claimed in any of the preceding claims in which the base is of the shape of part of a circularcylinder.

9. A tower packing element as claimed in Claim 1 or Claim 2, or any of Claims 5 to 8 each as appended to either Claim 1 of Claim 2, and provided with a plurality of tongues, the base being provided with a plurality of slots, and each tongue being supported from the base at an end of a respective slot.

10. A tower packing element as claimed in any of the preceding claims in which each slot extends substantially Darallel to the circumferential direction of the base.

11. A tower packing element as claimed in Claim 10 as appended to Claim 9 in which the slots are arranged in two substantially parallel rows.

12. A tower packing element as claimed in Claim 11 in which the tongues associated with the respective rows are staggered relative to each other in the circumferential direction of the base.

13. A tower packing element as claimed in any of the preceding claims in which two tongues are arranged such that they cross one another when the element is viewed in a direction parallel to the axis of curvature of the base.

14. A tower packing element as claimed in Claim 6, or any of Claims 7, 8 or 10 each as appended to Claim 6, in which the free end of the tongue is located substantially on the chord extending between the ends of the base.

15. A tower packing element substantially as described with reference to Figures 1 and 2 of the accompanying drawings.

16. A tower packing element as claimed in Claim 15 but modified substantially as described with reference to Figure la of the accompanying drawings.

17. A tower packing element substantially as described with reference to Figures 3 and 4 of the accompanying drawings.

18. A tower packing element as claimed in Claim 17 but modified substantially as described with reference to Figure 5 of the accompanying drawings.

19. A tower packing element substantially as described with reference to Figure 6 of the accompanying drawings.

20. A tower packing element substantially as described with reference to Figure 7 of the accompanying drawings.

21. A tower packing element substantially as described with reference to Figure 8 of the accompanying drawings.

22. A tower packing element substantially as described with reference to Figures 9 and 10 of the accompanying drawings.

23. A random poured packed bed comprising a plurality of packing elements each in accordance with any of the preceding claims.